Often brakes abruptly. The first time the car was set at 60mph adaptive cruise control when the car abruptly braked to almost a stop on a divided four lane hwy. I reported incidents to audi cary & put my car in for service. They did not find diagnostic conclusion. After picking up my car the problem continues. While on adaptive cruise control set at 62 mph abruptly decelerates to 17, forcing driver to pull into right turn lane. Again on same afternoon car braked abruptly with another car following closely behind, the driver accelerated, there was a pause where braking stopped but car did not accelerate, then the car accelerated avoiding being hit from behind. The last two incidents i immediately call audi cary to report the problem. I now journal all episodes of malfunction.